Recent discoveries on the key roles played by nitric oxide in diverse cellular functions in humans have generated tremendous interest in biologically active transition metal nitrosyl complexes have been identified as products after biosynthetic evolution of nitric oxide. They have been suggested as nitric oxide storage and found to be responsible for several important biological functions. However, studies are limited to EPR and IR identification of these complexes in solution, and the structures of these compounds at not well characterized and understood. The proposed research is to synthesize and isolate non-heme iron-nitrosyl compounds that mimic biologically active non-heme iron-nitrosyls by using ligands that contains amino acids of proteins such as imidazoles and histidines. The structures and reaction mechanisms of these complexes will be studied by a combination of physical chemical of physical chemical methods, such as FT-IR, EPR, NMR, UV-vis, X-ray crystallography, and electrochemical techniques. Chemical, photolytical and electrochemical methods will be used to elucidate the NO release mechanism from these complexes. The NO release kinetics will be investigated using a nanosecond laser photolysis technique. Moreover, water soluble ligands will be used to generate water soluble iron dinitrosyl complexes for potential medicinal applications. These results will provide information on the structures of biological active non-heme iron-nitrosyl compounds and, thus, help researchers in neuroscience, physiology, and medicine to understand the important biological functions of nitric oxide and its metal complexes. The kinetic data will be used to identify those NO releasing metal complexes, which are important in cardiovascular muscle relaxation, cancer therapy, and pharmacokinetic studies, as well as in other medicinal applications.